Line survey


Previous coral reef monitoring program implemented between 1988 and 2003 involved Line survey, which aimed to describe the profile of coral reefs and the vertical distribution of corals. At that time, three transect lines were placed from the beach in a direction toward the reef slope. Our current monitoring program took over these lines, except for the inner reef flat, in order to complement the photo-transect or the quadrat survey that do not cover the vertical changes in coral communities. Line survey has been continued in three year interval since 2006.

Line survey results
Download "Line_Survey_2012" (kmz format, 350 b)
Reef profile and vertical coral distribution pattern for each transect can be viewed on Google Earth
Download Google Earth

Line survey procedure

Line survey procedure

Line survey is conducted by a minimum of 4 scuba divers. The first diver lays a glass fiber transect line in the direction of the reef slope (10-15m depth) from the designated starting point near the reef crest. The second and the third diver place a 2m x 2m PVC quadrat along the transect line in 10m interval and photograph the quadrat with a digital camera. The fourth diver records the position of each of identified coral colonies within the quadrat. Digital images are analyzed using a PC with the software called Coral Point Count (CPC; Kohler and Gill, 2006; US National Coral Reef Institute, An observer identifies a coral occurring within the quadrat and trace its outline using either a tablet input device or a mouse. After entering the data into the PC, CPC automatically calculates projected area of each colony and generates a data table in EXCEL format. Percent cover of each colony is then calculated as the proportion of projected area against the area of the quadrat.

Line survey results

Line 1

Line 2

Line 3

Line 4